Tool exchange device for machine tool

ABSTRACT

The invention relates to a tool changer for changing tools between a spindle and a tool magazine of a machine tool. The object of the invention is to provide a simple and compact tool changer. A plurality of tool pots  19  are detachably held by a circular ring tool magazine  21 . Once the tool pot  19  receiving a tool to be changed is positioned at a predetermined position  39 , the tool pot  19  is rotated 90 degrees to the inside of the tool magazine  21  so that the axis of the tool to be changed is parallel to the spindle  7 . The tools are changed through linear motion and rotational motion of a tool changing arm.

FIELD OF THE INVENTION

The invention relates to a tool changer for a machine tool, such as amachining center, for automatically changing tools between a spindle ofthe machine tool and a tool magazine storing a plurality of tools.

BACKGROUND ART

Japanese Unexamined Patent Publication (Kokai) No. 8-323575 describes anautomatic tool changer, as a first prior art, which is generally usedfor machine tools such as machining centers. The tool changer comprisesa tool magazine, disposed at one side of a column of the machine tool,for accommodating a plurality of tool pots, each of which receives atool and moving the tool pots along an orbit to a predeterminedposition, and a tool changing arm for gripping the tool received in thetool pot positioned at the predetermined position and removing the toolfrom the tool pot with one of the grippers thereof. The tool changingarm rotates to the outside of the orbit so as to hold a tool received inthe spindle with the other gripper and to change the new and old toolswith each other. There is another type of tool changer in which the toolchanging arm does not rotate 90 degrees but a separately providedsub-arm rotates 90 degrees to move the tool pot to a changing positionfrom the tool magazine. Thereafter, the tool changing arm changes thetool on the spindle. In either type of the tool changers, the tools orthe tool pots to be changed is rotated 90 degrees to the outside of theorbit.

Japanese Examined Patent Publication (Kokai) No. 5-85298 describes anautomatic tool changer as a second prior art. A circular ring toolmagazine has a plurality of tool pots and is rotationally supported atone side of a column. A tool changing arm conducts various motions forchanging the tool on the spindle. The tool changing motion is composedof respective motions for holding a tool accommodated in the toolmagazine, removing the tool from the tool pot and rotating the toolchanging arm 90 degrees. A mechanism for conducting such various motionsof the tool changing arm is provided adjacent the tool magazine.

Japanese Unexamined Patent Publication (Kokai) No. 2001-71228 describesan automatic tool changer as a third prior art. A circular tool magazinereceives radially disposed tools in a plane with the tips of the tooloriented the center of the circle. The tool magazine is disposed on theceiling of a splashguard enclosing the machining area. The tool to bechanged is lowered from the tool magazine to a changing position where atool changing arm changes the tool with one on the spindle.

According to the first prior art, the tool or the tool pot is rotated 90degrees to the outside of the orbit of the tool magazine. Therefore, anextra space for allowing the tool changing motion is necessary at theoutside of the tool magazine. This is a problem for spacesaving.

According to the second prior art, the problem of the first prior art issolved. However, as described above, the tool changing arm must conductvarious motions. Therefore, there are problems that the configuration ofthe tool changing arm becomes complex and its size is increased.

According to the third prior art, the problems of the first and secondprior art are solved. However, because of the radial disposition of thetools in a plane, the number of the tools stored in the tool magazine isreduced compared with a tool magazine which has the same diameter andaccommodates the tools disposed perpendicular to the disk.

The invention is directed to solving the above-describe problems of theprior art, and the object of the invention is to provide a simple andcompact tool changer for a machine tool, the tool changer changing toolsbetween an indexable tool magazine having a plurality of tool pots forreceiving tools and a spindle.

SUMMARY OF THE INVENTION

In order to achieve the above object, according to the invention, a toolmagazine which rotates and indexes tool pots is provided, the tool potto be changed being rotated to the inside of the tool magazine, therotated tool pot being disposed parallel to the axis of a tool on aspindle, a tool changing arm changing the tool on the rotated tool potand the tool on the spindle with each other.

According to the invention, an apparatus for changing a tool between aspindle and a tool magazine of a machine tool, characterized bycomprising a tool magazine for storing a plurality of tool pots, each ofwhich receives a tool, the tool magazine moving and indexing the toolpot along an orbit; tool pot rotating means for rotating one of the toolpots, which is positioned at a predetermined position, to the insidefrom the tool magazine so that the axis of the tool pot is parallel tothe spindle; and a tool changing arm for changing tools between therotated tool pot and the spindle positioned at a tool changing position.

The tool magazine comprises a circular ring member for detachablyholding the plurality of tool pots along the inner circumferencethereof, a plurality of rollers for rotationally supporting the outersurface of the circular ring member and an actuator, connected to thecircular ring member, for rotating the circular ring member to index it.

The above-described configuration of the invention allows the spaceinside the orbit of the tool pots of the tool magazine to be used forthe tool changing motions. Further, only the rotating motion of the toolpot allows the axis of the tool to be parallel to the spindle, and aknown double-gripper type tool changing arm can change the new and oldtools. Therefore, a tool changer of which mechanism is simple andcompact can be realized.

Therefore, a simple and compact tool changer is realized with aconfiguration of a mechanism for holding a tool pot and rotating it tothe inside of the orbit and a known tool changing arm. The tool magazinecan be disposed at a forward portion of a machine tool compared with theprior art, and therefore, the space conventionally occupied by the toolmagazine can be used for the accommodation of the peripheral devices toreduce the space for the installation of the machine tool.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiment of the invention will be described below withreference to the drawings, in which:

FIG. 1 is a side view of a machine tool having a tool changer of theinvention;

FIG. 2 is a plan view of the machine tool of FIG. 1;

FIG. 3 is a partial perspective view of a main part of the tool changerof the invention;

FIG. 4 is a partial perspective view of a tool pot rotated to a positionfrom a tool magazine body; and

FIG. 5 is a perspective view of tool pot rotating means.

THE MOST PREFERRED EMBODIMENT

A machine tool is comprised of a bed 1, a column 3 mounted on the rearportion of the bed 1 for left-and-right liner motion in the direction ofX-axis, a spindle head 5 mounted to the column for up-and-down linearmotion in the direction of Y-axis, a spindle 7 rotationally provided inthe spindle head 5 for receiving a tool at the end thereof, a table 9mounted on the front portion of the bed 1 for back-and-forth linearmotion in the direction of Z-axis, that is the axial direction of thespindle 7, a pallet 11 detachably mounted on the table 9, a palletchanger 15 which is mounted on the frontal portion of the bed 1 holds apallet 13 for the replacement with the pallet 11 with a pallet changingarm (not shown) rotating in a horizontal plane, a tool change 25 with amagazine 21 which is disposed at the left side face of the bed 1 and hasa plurality of tool 10 pots 19 for receiving tools 17 and a toolchanging arm 23 for changing the tool mounted to the spindle 7 with oneof the tools 17 mounted to the tool magazine.

The machine tool processes a workpiece, which is mounted on the pallet11, through a relative motion in X-, Y- and Z-axes between the workpieceand the tool, mounted to the spindle 7, with the tool changer 25appropriately changing the tools. Once the process on the workpiece iscompleted, the pallet 13, on which a new workpiece is mounted, is put onthe table 9 by the pallet changer 15 for the subsequent process.

Next, the tool changer 25 will be described in detail. A frame 29 ismounted to the left side face of the bed 1. Four rollers 31 are providedon the frame for rotationally supporting a circular ring magazine body33. The magazine body 33 is connected to an actuator such as a motor 35through an appropriate means such as a belt, chain or a gear train so asto index a tool.

A plurality of tool pot retainers 37, each of which is comprised of leafsprings, are disposed along the internal circumference of the circularmagazine body 33 for holding tool pots 19. The tool pots 19 detachablyreceive tools 17 with known retaining means (not shown).

The tool pot 19 indexed to a predetermined position 39 is clamped by acylinder device 41 provided on the frame 29. Another cylinder device 45rotates the cylinder device 41 along with the tool pot 90 degrees abouta rotation axis 43 to the inside of the magazine 21 so that the tool pot19 is removed from the tool pot retainer 37 of leaf springs. The toolpot is positioned by contacting with a rest 47 provided inside of thetool magazine 21. At that time, the axis of the tool 17 held by the toolpot 19 is parallel to the spindle 7.

The cylinder device 41 moves, as shown in FIG. 5, a movable member 41 a,connected to a piston, to clamp the tool pot 19 with clamping members 41b and 41 c. By using appropriate means, such as an engagement between akey and a key groove, the tool pot 19 is always clamped firmly at thecorrect position. The cylinder device 45 has a piston rod 45 a the endof which is connected to the bottom portion of the cylinder device 41and the contracting motion of the piston rod 45 a into the cylinderdevice 45 rotates the cylinder device 41 90 degrees about a rotationaxis 43, the cylinder device 41 clamping the tool pot 19. In particular,the cylinder device 41 rotates between a first delivery position, shownin FIG. 3, at which the tool 17 is delivered relative to the toolmagazine 21, and a second delivery position, shown in FIG. 5, at whichthe tool 17 is delivered relative to the tool changing arm 23.

On the other hand, the tool changing arm 23 is provided on the frame 29for changing the tool 17 received by the tool pot 19 which is positionedat the rest 47 with the tool mounted to the spindle 7 which ispositioned at a tool changing position. The tool changing arm 23 hasgrippers 49 at each end thereof. The tool changing arm can linearly movein the directions indicated by arrows 51 and 52 in FIG. 3 (the axialdirection of the spindle 7) and rotates 90 or 180 degrees in thedirections indicated by arrows 53 and 54 (in the plane perpendicular tothe axis of the spindle 7). This can be carried out by a known mechanismwith a cam or a cylinder device, and therefore, the detailed descriptionthereof is omitted. The tool changing arm 23 is normally at a positionshown in the drawings at which the two grippers 49 are verticallypositioned. When a tool changing signal is delivered, the tool changingarm 23 rotates 90 degrees in the direction indicated by the arrow 53(refer to FIG. 3) so that the downside gripper 49 holds the tool 17received by the tool pot 19 which is positioned at the rest 47 and, atthe same time, the topside gripper 49 holds the tool mounted to thespindle 7.

Next, the operation of the tool changing apparatus will be described.The tool pots 19 of the tool magazine 21 receive necessary tools, andthe spindle 7 receives a tool which is used at the start of the process.The pot 19 receiving a tool for the subsequent process is moved to thepredetermined position 39. This tool pot 19 is positioned at the rest 47through the rotation of 90 degrees by the cylinder devices 41 and 45 andwait. When a tool changing signal is delivered, the tool changing arm 23rotates 90 degrees so that the grippers 49 hold the new tool received bythe tool pot 19 waiting at the rest 47 and old tool mounted to thespindle 7 at once. Next, the tool changing arm 23 advances in thedirection indicated by the arrow 51 to remove the tool 17 from the toolpot 19 and the tool from the spindle 7 at once. Then, the tool changingarm 23 rotates in the direction indicated by the arrow 53 by 180 degreesand retract in the direction indicated by the arrow 52 so that the newtool is mounted to the spindle 7 and the old tool is received by thetool pot 19 at once. The tool changing arm 23 rotates in the directionindicated by the arrow 54. The cylinder devices 41 and 45 rotates 90degrees to force the tool pot 19 into the blank tool pot retainer 39.The tool pot 19 is held by the leaf springs. After the cylinder device41 releases the clamped tool pot 19, the motor 35 rotate to move thetool pot 19, receiving the tool for the subsequent process, to thepredetermined position 39. Thereafter, the tool changing process will beexecuted through the above-described sequence.

The above-described configuration for rotating the tool pot 19 to theinside of the tool magazine 21 allows the tool magazine to be disposedat a forward position compared with the position of the tool magazine ofthe first prior art (the position shown by the broken line in FIG. 2).Therefore, peripheral devices, such as a hydraulic unit and an oiltemperature controller, necessary for the machine tool can be disposedat the position (the position shown by the broken line in FIG. 2) wherethe tool magazine of the prior art is disposed. Therefore, the footprintof the whole of the machine tool can be reduced. The peripheral devices,such as a hydraulic unit and an oil temperature controller, have notbeen disposed at the frontal position where the tool magazine of thepresent application is located because of the appearance of the machinetool.

In the embodiment, an example of the circular ring tool magazine hasbeen described. However, the present invention can employ a toolmagazine in the form of ellipse or a polygon with a circular cornerswhich goes around its perimeter. Further, the present invention can beapplied to vertical machine tools instead of the horizontal machinetool. In such a case, the predetermined position is set to the top ofthe tool magazine, the tool pot at the predetermined position is movedto inside of the tool magazine so that the axis of the tool is parallelto that of the vertical spindle. The tool changing arm is required tovertically move and rotate in a horizontal plane.

1. An apparatus for changing a tool between a spindle and a toolmagazine of a machine tool, characterized by comprising: a tool magazineincluding a circular ring for detachably storing a plurality of toolpots, each of which receives a tool, the tool magazine moving andindexing the tool pots at a predetermined position along an orbit; toolpot rotating means for detaching one of the tool pots, which ispositioned at the predetermined position, from the tool magazine androtating it to the inside of the tool magazine so that the axis of thetool pot is parallel to the spindle; and a tool changing arm forchanging tools between the rotated tool pot and the spindle positionedat a tool changing position.
 2. An apparatus for changing tools of amachine tool according to claim 1, wherein the tool magazine comprises acircular ring member for detachably holding the plurality of tool potsalong an inner circumference thereof, a plurality of rollers forrotationally supporting the outer surface of the circular ring memberand an actuator, connected to the circular ring member, for rotating thecircular ring member to index it.
 3. An apparatus for changing tools ofa machine tool according to claim 2, wherein the tool magazine furthercomprises pot holding means including leaf springs, disposed along theinner circumference of the circular ring member, for engaging the outersurface of the tool pots to hold them.
 4. An apparatus for changingtools of a machine tool according to claim 1, wherein the tool potrotating means comprises a clamping member for clamping the tool potpositioned at the predetermined position, a first cylinder device formoving the clamping member between a closed position where the clampingmember clamps the tool pot and an open position where the clampingmember releases the tool pot and a second cylinder device for rotatingthe clamping member about a vertical axis between a first deliveryposition where the tool is delivered relative to the tool magazine and asecond delivery position where the tool is delivered relative to thetool changing arm.
 5. An apparatus for changing tools of a machine toolaccording to claim 4, wherein the tool pot rotating means comprises astop member, provided at the second delivery position, for stopping therotating movement of the clamping member.